In high frequency oscillators stray capacitances and lead inductances become very important in determining the oscillation frequency, output power, feedback fraction and other ac quantities. High frequency oscillators heretofore provided have a variable capacitor or a variable inductor in the tank circuit. These oscillators are assembled and then the variable capacitor or inductor is adjusted for the desired performance. Prior known adjustable or trimmable devices often have stray capacitances and inductances larger than the capacitances and inductances of the main tank circuit components, thereby limiting the maximum useful resonant frequency of the oscillator.